Reciprocating electro-magnetic motor



INVENTOR (Ziand/C Parker Aug. 1, 1961 L. c. PARKER RECIPROCATINGELECTRO-MAGNETIC MOTOR Filed June 27, 1956 United States v Patent i2,994,792 RECIPROCATING ELECTRO-MAGNETIC MOTOR Leland C. Parker, Elmira,N.Y., assignor to The Bendix Corporation, a corporation of DelawareFiled June 27, 1956, Ser. No. 594,232 2 Claims. (Cl. 310-18) The presentinvention relates to a reciprocating electromagnetic motor, and moreparticularly to a device of this type which is especially adapted foroperation as a piston pump.

Piston type electrical fuel pumps such as shown for instance in thepatent to Dickey et al. 2,472,067 have attained wu'de commercialacceptance, but in such a highly competitive field economies in materialand fabrication, and improvements in operation are very important.

In devices of this kind as heretofore constructed, the control of theelectro-magnet which actuates the pump piston has commonly been eitherby some device which is extraneous and independent of the movement ofthe piston, or by means of a permanent magnetic element which senses themovement of the piston, While the first form of control has certainadvantages for some types of use, the second form is at present moreprevalent in spite of the fact that the permanent magnetic element andits mounting means form important items of the cost of the device.

It is an object of the present invention to provide a novel device ofthis character which is simple and economical in construction andeflicient in operation.

It is another object to provide such a device incorporating an improvedform of means for controlling the actuation of the pump piston.

It is another object to provide such a device in which the movement ofthe piston is employed to control the energization of the actuatingmeans in a simple and effective manner without utilizing any permanentmagnetic element.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in which:

FIG. 1 is a vertical substantially mid-sectional view of a preferredembodiment of the invention, showing the electrical circuit indiagrammatic form; and

FIG. 2 is a section taken substantially on the line 22 of FIG. 1.

In FIG. 1 of the drawing there is illustrated an electromagnetic pumpcomprising a non-magnetic cylinder 1 in which a hollow magnetic pistonplunger 2 is slidably mounted. A spring 3 is arranged to normally holdthe piston against a yielding stop member 4, and an electromagnet 5surrounding the cylinder 1, is arranged when energized to draw thepiston 2 down against the force of the spring 3.

The cylinder *1 is mounted centrally in a casing 6 of magnetizablematerial by means of pole pieces 7, 8. The casing 6 forms an inletchamber 9 and an outlet chamber 11, and check valves 12 and 13 connectedto the cylinder 1 and piston 2 respectively, cause reciprocation of thepiston to transfer liquid from the inlet chamber to the outlet chamber.

Means are provided for intermittently energizing the electro-magnet 5 tocause reciprocation of the piston. As best shown in FIG. 2, this meanscomprises a battery 14 grounded at 15 and connected through a manualswitch 116 to the electro magnet 5, here indicated diagrammatically. Theelectro-magnet is connected by a lead 17 to a spring blade 21 mounted onthe upper pole piece 7 as indicated at 22, but insulated therefrom. The

spring blade 21 carries a contact 23 which is normally in engagementwith a contact 24 on a shorter and stiffer spring blade 25 which is alsomounted on the upper pole piece 7 and is grounded thereon as indicatedat 26.

An armature member '27 formed of soft sheet iron is pivoted as shown at28 on the upper pole piece 7 for horizontal movement toward and awayfrom the pump cylinder 1. The armature 27 is in the form of a leverhaving its fulcrum at the pivot 28 and having its long arm 29 curved toconform to the exterior of the cylinder 1. The short arm 31 of the leverhas a pin 32 of suitable non-conducting material fixed thereon inposition to engage near the free end of the contact spring blade 21,whereby the pressure of the blade 21 on the pin 32 normally holds thelong arm 29 of the armature away from the cylinder 1 and against a backstop 33 as illustrated. When the armature is drawn against the cylinderby the attraction of the magnetic flux of the piston 2, such movementcauses the pin 32 to separate the contacts 23, 24 and thus deenergizethe coil 5.

In operation, starting with the parts in the positions illustrated,closure of the switch 16 causes energization of the coil 5 whereby thepiston 2 is drawn down, cocking the spring 3. When the top end of thepiston has been thus moved down to substantially the level of thearmature 27, the concentration of flux from the electromagnet at the endof the piston becomes eifective to attract the arm 29 of lever 27 andthereby open contacts 23, 24. The collapse of the flux through the coil5 then permits the pump spring 3 to accomplish the return or pumpingstroke of the piston 2. At the same time the armature 27 is released,permitting contacts 23, 24 to close, whereupon the operation isrepeated.

It will be appreciated that there is here provided an actuatingmechanism for the control contacts of an electro-magnetic pump in whichthe operation of the contacts is a function of the stroke of the piston,although no permanent magnetic material is used to sense the movement ofthe piston in its cylinder.

Although certain structure has been shown and described in detail itwill be understood that changes may be made in the precise form andarrangement of the parts without departing from the spirit of theinvention.

1 claim:

1. In a reciprocating electromagnetic motor; a vertically disposednon-magnetic cylinder; a magnetizable piston of low magnetic reluctanceslidably mounted in the cylinder; a stop adjacent the upper extremity ofthe cylinder defining the normal position of the piston in the cylinder;yielding means urging the piston towards the stop; an electromagnethaving an upper and lower pole piece surrounding the cylinder and pistonand defining a spatial separation between the stop and the upper polepiece, said electromagnet arranged, when energized, to magnetize thepiston and draw it into the electromagnet away from the stop with an endof the piston positioned in the spatial separation adjacent the upperpole piece; and means within the spatial separation actuated solely bythe magnetic attraction of the end of the piston as the piston ismagnetized by the electromagnet for controlling the energization of theelectromagnet including a pair of resiliently supported normally closedcontacts and a movable magnetizable armature in the form of a leverpivotally mounted for movement towards and away from the piston end asthe end approaches the upper pole piece so as to be attracted towardsthe said piston end responsive to energization of the electromagnet,said lever having pin means operatively engaging one of the resilientPatented Aug. 1, 1961.

contact supports to open said contacts as the lever moves towards thepiston end.

2. A reciprocating electromagnetic motor as set forth in claim 1 inwhich said resiliently supported contacts are mounted on springcantilever arms normally pressing said contacts together, one of saidarms being substantially stifier than the other, said means for openingthe contacts being arranged to move the more limber arm away from thestiffer arm to open said contacts.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Great Britain Oct. 16, 1931

